$col-span: 100 / $col-span-max;

.s-col {
  min-height: 1px;
  box-sizing: border-box;

  @for $i from 1 through $col-span-max {
    &--#{$i} {
      width: #{($col-span * $i) + "%"};
    }

    &--offset-#{$i} {
      margin-left: #{($col-span * $i) + "%"};
    }
  }
}